CA1201926A

CA1201926A - Process for coloring (printing) of web-like objects, especially ski coverings, as well as similar objects

Info

Publication number: CA1201926A
Application number: CA000370196A
Authority: CA
Inventors: Horst Custor
Original assignee: CP-COMPONENTS GmbH
Current assignee: CP-COMPONENTS GmbH
Priority date: 1980-02-07
Filing date: 1981-02-05
Publication date: 1986-03-18
Also published as: DE3004518A1; DE3066524D1; ATE6140T1; EP0033776A3; EP0033776A2; NO810386L; EP0033776B1; US4462852A; CH629704A5; DE3004518C2; JPS56121789A

Abstract

ABSTRACT OF THE DISCLOSURE

PROCESS FOR COLORING (PRINTING) OF WEB-LIKE OBJECTS, ESPECIALLY SKI COVERINGS, AS WELL AS SIMILAR OBJECTS

The invention refers to a process of coloring (printing) of web-like objects, especially ski coverings of thermoplastic, such as olefins, especially high and low pressure polyethylene where, the layer is broughtcontinuously as a hot foil, essentially in a state of fusion, in contact with a print carrier, on which there has been deposited a print pattern of a dye which transfers first by sublimation and then diffusion. A transfer of the dye onto foil occurs in a short time and only essentially along a small areal strip perpendicular to the common direction of conveying of layer and print carrier. It is preferred that the transfer of dye occurs in the gap between rollers through which the foil and the print carrier are guided. This allows the obtainment of warpage-free print patterns on relatively thin-walled web-like objects in a continuous process, where it is assured that no warpages occur after cooling or reheating of the printed layer. Also, migration problems are avoided by means of short-term locally limited penetration under high pressure in the roller gap.

Description

- 1 - 1372 P/~ CA

PR~CESS FOR COLORING (P.RINTING) OF~ WEB-LIKE cBJEcrs~
F~E~CIALLY ~ CaVERINGS, AS ~EIL AS S:C~L~R (~S
~e inven~ion relates to a proce~s for coloring (printing) of wek-l~ke objects, especially ski cov~rings, rcm thermc-plastic such as olefins, esl~3cially high and low ~ressure polyethylene, where ~he side of the covering t~ ke ~r.inted o~ is ~roug~t in co~tact with a pri~t ~ ier. Ih~ print carriler has a coating the~eon compris.~ng at least one color p.igment whi.ch, under the i{~luence of heat, is at first sublimable and then dif.~usable~ whereby the color is transferred frcm the print carr.ier -~o the web. The invention furthe~r relates to apparatus or the implementation of such a p~ocess and to printed web-like objects~
~s is generally kn3wn, so call0d mLltiple layer skis have been n~nufactured for some time ~y glueing several layers togeth~r (~ee for example DE-OS 2 804 943) where these layers resp~ctivel~
form a lower, central, and upper structure.
- The central structure generally consists o& a wcod or h~rd foam ~ore, which is sideways pressed in with duro-plastic synthetic resin;
- The upper struc~ure generally consists of an aluminum sheet and/or laminate of fiberglass re~ ~o~ced plastic qlued to the oore, on which a plastic~foil covering is applied, which is decorated in subsequent w3rking processes;
- The lcwer structure on the other hand consists o an al ~ um sheet or of a layer of fikerglass reinforced plastic, which is glued on ane side ~o the co:re and which on the ot~er side ~possibly throug~
s~veral more layers) is glue~ with the proper ~ 2 - 1372 P/~

runner layerO which normally is a transparent synthe tic resin ct~vering ~f 1 - 2 mm thicknes~
and prefexrably o~ p(:)lyethy~ene, namely high or ~ ow pressure pc>lyethylene, or p~lyt:etra~luc)re$hylene (~e:flon, Trademark~
~ormall~r the inner side of the runner layer ~ or also of the t~p covering) is printed, e.specially with a ~ nu-fact~lrer, type designati~n~, etc~,; this printing i~
visibl~3 thrc~ugh ~he transpar~ent layer or cover~ng.
Urltil n~w, essentially only high and ~ pressure poly-ethylene ski covering~ were used.
The decoration~, especially the printing o~ such layers and further wl~rk processes has been done until now ver expensively ( see DE-OS 2 804 943~ arid still results of ten in bad quali~:
- :Lt is done piecewise, that îs not ~c)ntinuously ~x endle~;slyr namely through screen pressure (:Erc>m patterns, lettering or the like~ with epoxy pressure color5, where in additi~n the layer has to be treated before printing such as thermally (flame c~ntact3~
elec~rically (Corona-discharge) ox ~hemically (etching3, since o~herwise the tepoxy~ print c~lor woula not adher~;
After ~he printing process a drying time of 10 - 20 . hour~ is ne~essary after which the printed and drie~
layer is ~rea~ed with an ~paque ~colored) epvxy-containing casting material (an opaque coverlng lacquer) incl~ding a hardener, in order to produce a background colox layex f~r ~he transparent covering;

'~

1372 P/~ C~

- this casting matexial layer is then glued to a layer of fibergl~ss reinforced plastic, howevex ~nly a~ter seveial hours ater ~hich the solvent material has c~mpletely left the casting material which means after the mass- has hardened.
Inspite of this ~abrication process~which is especially demanding,it has not been p~ssible tv secure a printing quality o good continuity on the completed ski.
. The foll~Ying deficiencies occur rather late, namely 3 to 10 month5 a~ter manufacture o~ the ski:
- insuf~ic.ient adhesion preparation ~ the coverlng before printing~
- Attack ~ the printed p~cture by the adhesive s~ that c~lor tones are changingJ-the c~ntours of the printea 15 . pic~u~e bec~me diffuse or cracks develop in the prin~ed arrangement - insufficient elasticity o~ the cas~ing material relative -$he cs:~vering or insufficient adhesion o~ the opaque casting material on the p~lyethylene o ~he covering s~ ~hat the ~e-. paratic~n of the c~as~ing matexial manifests itself in the form of light spDts on the ruImer side;
- insufficient evaporation c~ he solvent iErom lthe opaque casting mass which causes adhesion ~3eficiencies because o~ ! format;on ~ bubbles bstween the casting mass and f~r example the p~lyethylene of the coverin~, thus prc~-~ucing bad lc~oking light spots ..,,.. ;~"
~.~

3~

- ~ - 1372 P/~ CA

Similar difficulties as with the r~unner covering occur when a corresponding top cover which is to be decorated is used as a top covering layer.

mese difficulties as of this day (inspite of a least 10 years experience) sti]l pose a serious problem, since the cause of the deficiencies has not been researched in detail, so that there often results claims fran the ski buyer against the ski manufacturer.

Finally, the best obtainable-print ~uality is very limited and relatively expensive, and the printing of photographs with half tones is practically impossibleO

me transfer printing process in accordance with DE-C~S 2 642 350 is relatively deman~ing and very difficult to control, where the surface to be printed on is first covered with a thermoplastic synthetic resin layer such as poly-urethane or polyester which can be printed without difficulty, this being done to avold conveying by migration.

It is taught in DE-C~S 2 731 121 to print on polyethylene by bringing the side of the form memker to be printed on in contact with a print carrier such as paper print carrier, with applying hea-t to obtain a fusion deposit where there has been applied to the print carrier a printing pattern of a dye which transfers first by sublimation and then by diffusion.
Preferred temperature 160 - 220C is given. As a "sufficient"
contact-pressure duration of the print carrier against the surface to be printed on, 5 - 30 seconds is suggested. However, under these - 5 - 137~ P/~ C~

con~itions given in DE-OS 2 731 121 the same migration problems arise which one tries to avoid in accordance with DE-OS 2 642 350 by separately applyi~g layexs tl~ the side to be printed vr~ . ' 5 Obvious~ y~ ~e migratlon problems l~ccur because of arl excessively lony c~ntact pressure time under high heat where~s on the other halld a relatively high contact pressure is requ.ixed tc~ obt~in ~uf:E.icient penetration of ~he dye stuf :iE into the f onn merr~er ~.
~len w~rking the process as described in DE-OS 2 731 121~ one fin~s that yl^eat ~hermal stress in the .fonm of sbres~
peak~ develop in the f~rm member due to the fusion depDsit t)f the surf~ace ~o be printed Dll, ~-hich makes it impc~ssible to print on re~atively thin walls, for example 15 w~b -like c)bjec~s, especially ski laminations. ~n extreme s~res decrease occurs in the area o~ the boundaryline be~ween ~he fused pressure side and the lo~er side ~hich s~ill is in a S~lid state t where t~e decrease of tension results in ~-arpage of the printed layer during co~ling.
20 Besides ~he warpage pr~blem sc> ~ar described, there c)ccurs with "form iEree" printing ~f thin walle~l objects the prc>b~
lem that tha paper print carrier when pressed on longer ~an ~ne second becomes partly unremovable from the ~use~on s~nthe~ic resin, when using thin paper print carriers as ~mployed in the printing of textiles~ ~he printed surrace then is essentially unusuable, F inal 1YJ it i s anokhex disc~lvantage of the ]~ solution .~ n accordance with DE-OS 2 731 121 khat "an outer second heat application~' i5 required for printing~ The form member to - be print:ed on must be fus~od on the pre ssure side by means of ~a heating plate or the like.
Thereforet the prc>cess ~;no~n from D~:-OS 2 731 :121 is, for the abcve reasons, not suited for coloring or print:~ng of we~ -liXe objects~ e~;pecially ski covexing~i, The object of this invention is a process and an apparatuS of the above mentioned nature which provides shalpness of contour and warpage~free gloss prints where no warpage di~ficulties ana no difficulties develop duxing the removing of a paper print carri.er from the hot f~il after the colDr transfer r :L5 It .is further the object o F this invention to de{relop printed web -like objec~s, especially ski overing, froi;~ thermo-plastic, such as olefin and the like, ~hose print is free of warpage alld which stand oult :because of good fixation o:E the print color and whose print side ~an ~e glued to a ski me~iber ~r the li~eO per~ectly and permanently .
l~he process of the given task is surprisingly accomplished with ease by ~he covering bein~ altv~e~her in the ~orm ~f a hot foil essentially in state o~ fusion, a sp~t c~ntinu~usly . in contact with the print carrier, wi~h transfer o~ the color to the ~oil taking place ~ver shor~ time and then ~nly essentially along a. ~arrow area. strip perpendicular to the co~mon direction of c~nveyance o the layer and the print carrier~

~ 7 ~ 1~72 P/~ CA

T~-e object to he printed on i~ thus in thi~ invented process cc>mpletely in a state of fusion so that a uni:fvrm crystallisation occurs over the cross f;ectic)n during cooling. ~O thermal stress can develop in the process of this inventionO

Sticking of the }3rint carrier i5 avoided even with high printing pressures by the shoxtness c)f kime of the print transfer. Thi3 gu~rantees an intensive local. penetrati~>n of the dyes into ~he layer or t'he h~t foil. Surprisingly~
1~ no miyratic~n can b~ fourld. Fur~hermore, n~.synchri~nisation prc~blems be~een the hot -El~il and the prin$ carrier~, which would result in warpaye prc)blems,oçcur in the process c>f this invention, because of the short time of print transferO
Obtained are high gl~ss prints of highest quality ~hexe ~he half tones are retained without defect,.
It is surprising that the above mentioned advantages are also obtained by printing on layers of high and low pressure poly-.
ethylene~. Tests have sh~n that ra~er gc~od print qualities - are obtained ~-hen printing on a rnixture of highest and high molecular polyethylene (molecular weight 6 X 105 and 20~i X
lt)5) . The print dye at the printed areas is diffuset3 in~ard, fs:~rming print patterns of sharp contc)ur, sc> that an inter-îerence c~f the connection of adhesic~n by the print dye dDes not occur bet~-een the pxinted side of the layer and, fDr example,the upper ~r lower side ~f the ski b~dy.
Preferably, a t3~a~e con~oll~ cooling of the print~- --foil occurs in a second process of longer duration. Through this step crystallisation through the entire thickness v 1372 P/~ CA

the printed Eoil is enhanced. me thermally controlled cooling avoids especially the inclusion of thermal stress pockets which, for e~ample, could form due to excessively fast cooling.
Surprisingly, ~he invention permits synthetic resins to be printed upon directly without necessitat~ng a preconditioning step as has been used heretofore for this plIrpose, such as the influence of electrical discharges, chemlcal agents (for example t~rough etching) or the like.
For ex3mple, in a process for coloring, printing, and painting of form bodies of polyolefins and polymerized mix*ures of olefins (see DE-PS 1 153 6S8) very special color dyes clre deposited on the form body and which are, after the initial drying of the dye to ~le form bcdy, heated to a temperature below the crystallite fusion point of the polymer, which per examples given is c~bove 100C cm ~ which is active for 3 - 10 minutes.
The appLication of special color dyes and the de~cribed process are to avoid an excessive "bloaming, migration, and diffusion ~bleeding)" of the color dyes. The difficulties d~ring the printiny of olefins are not only found in ~E-P5 1 153 658 in the small vicinity of the colored dye for polyolefins, but they are also found in the strong migratio~ (see column 1, lines 11, 12).
An especially advantageous apparatus for the implementation of the i~vented process is marked by a pair of rollers for the formation of a roller gap where one roller is partly wrap~ed by the foil and the other roller is partly wrapped by the print carrier, and drive arrangements for the tw~ rollers, for driving them essentially at ~he same circumferential speed.

D

The apparatus of the invention allows a short time contact bet~een foil and print carrler in a cont:inuous process where the contacting ~nly occurs along a narxu~ areal skrip per pendicular to the comm~n directiQn o conveying ~f *he layer and the pr.int carrier thxough ~et~een ~he t~o rollers~
Further advantageous emb~diment~ of the invention are des-cxibed in mo~e detail i.n the fol~owing sub-claims whose teachings have proven them5elves superbly in practice.
The teaching in aecordance with Claim 13 advc~nces a print pattern on the foil with sharp c~ntours and free .
of warpage, by ~voi~ing a possible srnall existing rQtat.ion of the used matter in the reservoir zone in the roller gap (especiall~ in the case of laxger differences in the dia-meters of the ts~ rollers)~ ~A relative mt~ki~n o:E O magnit~de is guaranteed between dye stuff and fusion elements. The teaching in accordance ~-ith Claims 15, 16 ~ 28 is es ~ ~.ly advantageous to avoid teaxing, warpage or ~rumbling of the - print carrier~ ~-hile it passes through the fusic>n matter reservoiru- Especially in accordance with teaching per claim . 20 17 no disl~dging of the prin~ carrier relative to the con-.
veying means can occur which also assures one of zero re-lative speed be~ween the hot foil ~especially extrllded fusion layer~ and print carr;er, tha t is their synchronQus speed~
Through the teaching in accordance with Cl~m 24 the str~h of color of the printing (force of color) is further increased or a better color contrast is 3~tained~ In additionO this ~verpasting or glueing allows an insignificant passage ~f print color from the layer (foil) into the adhesive and/or the reinforcing means, which~howevex,even fixes deeper the print pattern in the completed binding elemen~.
Regarding the special advantages o~tained from the teaching - 10 - 1372 P/~ CA
of claims pertaining to the apparatus I it is essentially referred to the c~rrespnding proces~ claims.
The embodiment ~f C laim 3~ allo~-s post-printing on completed (cold) foil~ where f~r reasonS of expe~iency the heated pxessure rollers are used simultane~sly for contact of the fo~l and the print carriex a5 well a5 tempering o the foilO
~he invention is further explain0d witn reference to illustrated embodiments wherein:

Figure 1: A schema~ic of a first example of embodiment of an appara~us for the implementation o~
the invented process:
Figure ~: A se~tion of Figure 1 ~-ith pertinent diagrams ànd parameters for explaining the invented process .

3~;

~ 1372 P/~ CA

Fig~re 3: Detail of a variatiorl of the aF~karatus from Figure l;
Figure 4: a further variation of the apparatus of Figure l;
Figure 5: a third variation of the apparatus o~ Figure l;
and Figure 6; a fundamentally different embodiment of the invented apparatus.
Referring now to Figure 1 in detail:
From extrusion tool 1 issues a foil 2 of thermDplastic synthetic resin in form of a fusion sheet. An assistant prin-t carrier 3 - is rolled off a supply roller 4 and a conveying roller 5 to a roller gap formed by heated roller 6 in which it is brought in contact with foil 2 in form of a fusion sheet. The roller gap is sized in such a way (see for more detail Figure 2) that a wedge-shaped reservoir 2a is formed as can be plainly seen from Figure 1. In reservoir zone 2a the beginnlng of the contact occurs as already described in detail in the introduction.
Foil 2 with the assistant print carrier 3 exits from the roller gap between the two rollers 5 and 6 to a second stage im~ediately adjacent thereto, in which foil 2 and the assistant print carrier 3 together run over a relatively large circumferential angle of roller 6 ~herein there is provided in a tempering arrange~ent 7, a controlled reduction of temperature ~ram the roller gap in the direction of motion unt;l the assistant print carrier has its print pattern exhausted, follGwing which it is removed cver a b1rn-aroun~ roller 8 to a storage roller 9.

~, Ç;

~ 1372 P/9 CA

The prin~d foil 2' preferably then is moved past a - post treatment apparatus 12 in the fonm ~f a high freq~ency Corona discharge or non~oxydizing flaming~ Subsequently the printed foil 2' i5 wound ~n storage r~ller 11 after passing over a ~rn-around roller 10, to be further proces~sed later on.
Although rollers Sf 6 are shown with essentially the same diam~ter, it i~ und~rstood that their diameter can be absolutely diferent3 ~r examp:Le~the roller 5 ean have a consiaerably smzller diameter than roller 6.
The temperature arrangement 7, whlch ls shown only schema-tically,can,for example,be formed by a co~l air channel where the cooling air ~an be introduced at the end identi-f i2d by an arrow.
~he post treatment arrangement 12 has its ~-n fundamental structure.
In the example ~f -~e ~ ~t Fig. 1 the print carrier is a so ealled assistant print earrier 3, in that after . giving off its print pattern to the print-reeeiving ~oil

2, it is removed ~rom conta,cting foil 2~namely over turn-around roller 8 to th~ storage r~ller 9, as already ex-p~ained. Howeverf i~ i~ also possible to let the print carrier 3 form a permanent b~nd ~-ith foil ~, if~for exampleg print carrier 3 has to perform further functionsv In this .25 case the turn-around roller 8 and the storage roller 9 would be deleted in ~igure 1.

With reference to :Figure 2:
The preferred embodiment of the invention or a print-receiving polye~hylene f~il i5 shown in Fig, 2 in ~ore

3~ detail as now will be explained.

~' ~ 13 - 1372 P/~ C~
The syn;bolsu~;ed in Figure ~ have the foll~-ing meaning:
:E = Opening width of ~xtrusl0n tf:)ol lt - ~ = Wid~h o:~ rt~ller gap ~at ~e narro~-eSt locatic~n~
belt~-een ro:l ler 5 and ~, ~
~ ength o roller gap betwE~en xoller S and 6 -- d = Thickness o: ~oil 2. .
As evidellce in Fig .. 2 3the :rQller length 1 should be clearly u~erstood to be t~:ie l~g~h of the reservo~r zone 2 a, name~y on one hand bet~-een tlle :~ir~t incidence ~f contact of oil 2 in direction of conveyance ~ see arr~l ~n circumference o:E roller~; S and 6~ and on the other h~n~
the m~st ~arrow location ~:E the rc~ller gap correspvnding to rl~lïer qap wiat~ S t ~;eF~ Fig . ~ t:he two d~t~ed lines ~-hich border double arrow 1~"
~; The f~ lolh-ing relatic~nships exist amGng the individ~lal parameters s ~ d = kls ~e kl is a constant -i:n the ra~ge 1,0 to 1~2 1 - k2s where k2 is a constant in the range l t~ 10 p identifie~ the line-pressur{3 c~ver the circum~erence of rollers 5 and 60 The temperature distributiDn of foil ;! over the circ:um-ference oi~. roller 6 i5 seen. f~c~m the t::orrespc~ndiny diagram ".ol1 temperature ' in Figure 2. This temperature ~i3;tri but;cn is det:ermined by the act that foil 2 which issues iErl~m extrusior~ to~ 1 at a h;gh temperaturet namely at apprc~x,, 225 C ~ r high molecular p~>lyet}tylene~cc~ols C~
upc~n exit rom the roller gap, inspite o~ heat:- !transfer ~rom rollers 5 2nd 6,~ which ( for e;cample by means of oil recirculati~n heating) are hea~ed to temperatures :E~r example of approx,D 70 C and 110 C respectively~
I~ can be seen :Erom Figl, 2 thalt the :E~irst ~nstanee of conta~t ~ccurs ~ the vicinity ~f th~ roller gapO as it is formed by circumferen~al arc~ of lSs~ and 105> ~see the i 137~ P/~

graphical represent~tion ~4-ithin rol~er 5~ since there the required hi~h pres~ure (m~re ~ccurately: line pressure P
due to the con-tacting called for ~7 the invention of foil 2 and pressure carrier 3 in a strip~shaped, that is in an 5 . es~entially linear zone) ~ and the necessary high temperatuxe exists talso see the foil temperat~re curve within roller 6 with high values in circu~ferent~al arc from O - 15 after the most narrow position o~ the roller gapO
A~ter that the pressure adjustment iG not critical.
Application of tempering arrangement 7, which~x e~ample, can be ~ormed by means o~ a ~-arm air channel ox through in:Erared radiatc~xs, .is recortlmended for adjustrnent of th~
. temperature distribu'ion of foil ~ in the second stage of the contacting process, so t~t the foil with -the printed-on patter~,durina its cooling~is temperature con-trolled frc~n therln~elastic to solid state in such a fashion, that no warpage of the foil or the printed pattern occurs~
The rotational speed, that is the circumferential speea of ~he t~io rollers 5 and 6,should be ad3usted in-such a way that zero relative-velocity between foil 2 and the print carrier 3 results and therefore a clean print is ~btained .

With re:Eerence t~ Figure 3:
The arrangement of the extrusion tool 1 with its ~pening relative to the roller ~ap bet~een r~llers 5 and 6 is such that the angle of introduction of foil 2 is approx. 10 -relative t~ the cen~er line of ~he roller gap, ~hat is in th~ direction to the conveying xoller 5 of the assistant print carrier 3.

This measure results in the advantages described in the introduction.

With reference to Figure 4:

:Cn this em~odiment of the invention, additional refinements are m~de relative to the embodimerlt of Fig. 1; which ccmprise a disc 14 and brake shoe 15 operatively connected to brake shaEt 13 Additionally a brake lining 5a on conveyor roller 5 of print carrier 3 is used for tensio~ control and a pre-heat arrangement 16 fF preheating of print carrier 3 to approx. 50 - 70 C.

With reference to Figure 5:

Here there is shown a modifi~d pressure arrangem~nt intended for an improved contacting, that is holding together of foil 2 and print carrier 3 in the second stage, the pressure arra~gement being formed by pressure rollers 17 to which is added a te~pering arrangement in the form of a hot air channel 18, so that the indicated temperature decrease in the direction of conveying results in reference to several pressure îollers 17.

With reference to Figure 6-This =mbodlmant is fundamentally different compared to Fiy. 1 in that foil 22 is not set from an extrusion tool but rather that it is unreeled initially from supply roller 21a in a cold state and then reaches over turn around roller 24a a pre-heat roller 26 where the foil is heated akove its crystallite melting point, that is finally after passing ~D

3 ~ ~j ~ 1372 P/4 CA

another tur~ aroun~ r~ller 27, enters the rDller gap f~rmed by two embossing roll~rs 35, and 36 while ~imultane~usly a print carrier 23 is led in~o ~he xoller gap where the print carrier ha~ been unreeled from a supply roller 21 b over .
turn around roller 24 b ~nd a preheat roll~r 25~ which pre-heats to approx. 50 - 70 C.
The irst contacting bebween the foil and print carrier OCCUr5 in khe gap formed by the two glazing rollers 35 and 36.
- SubsequentlyO :Eoil and print carr.. iex run t~rough a pressure arrangement 3~ where preferably tempering occurs through pre~sure rol~ e.rs 37a and 37b by h~ating t~lem ac:cordingly, while the pressuxe rollers to the left in Figc, 6 have a lower temperature than those on ~he right ~ide ~f Fig. 60 The print-exhausted prir~t carrier 23 is stored on a storage roll 39 by means of a turn-around roller 38~ whereas printed foil 22~ is s~ored on storage xoller- 41 by means of turn around r~llex 40 and 40av This example Df the e ~ odiment maXes it p~ssible to print on a foil which has b~en produced previously.
Regarding f~rmation of the roller gap between the ~wo ~lazing rollers 35 and 36,~ preferably similar c:onsideratiorls apply as in regard to the above Fig, 2~ except tha~ here the foil thickness d is used ln place o~ extrusion tool ~penin~ wid$h f.
e process of the invention m~i be carried out using a double `:kand press (for example of the firm Sandvik) which is 3Ad6 fundamentally kno~-n on its o~n meri^t, which contains a combined starting pressure arrangemerlt for heat treatment, as long as specially high values of pressure and temperature are set in its direction of conveying in the first stage, in order to implement the invented process of the first stage of the in contact~bringing of :Eoil and print carrier~
In addition, roller 6 or the glazing roller 36 can be equipped with a mint pro~ile, to accompl:ish simultaneously with printing of foil 2 or 22 an additional embossing of the foil later to be used as a layer, :for example,when the layer :is to ~e equipped ~-ith scales f~r long distance ski racing~

~\

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for printing oF web-like objects especially ski coverings from thermo-plastics, such as olefins including high and low pressure polyethylene where the side of the web-like object to be printed is subjected to a print carrier wherein simultaneously at least the side of the web-like object to be printed is under the influence of heat .so that it is melted, the print carrier being covered with a printing pattern of at least one color pigment which under the influence of heat is first suiblimable and then diffusable, comprising conveying the print carrier continuously into short-term contact with the web-like object whilst in the form of a foil essentially in the state of melt, and transferring rapidly the color onto said molten foil essentially along a narrow area strip perpendicular to the common direction of the conveying of the web-like object and the print carrier.

2. Process in accordance with Claim 1 wherein the tempera-ture of the printed foil is reduced in a temperature controlled stage.

3. Process according to Claim 1 wherein the short-texm contacting process for transfer of color is accomplished in a slot that converges in the direction of conveyance which together with the velocity at which the foil and the print carrier are conveyed is controlled in such a way that there results an essentially static wedge-shape reservoir zone of molten foil.

4. Process in accordance with Claim 1, 2 or 3 wherein the web-like object is extruded immediately prior to the printing process.

5. Process in accordance with Claim 1, 2 or 3 wherein a cold foil is reheated to provide said molten foil.

6. Process in accordance with Claim 1, 2 or 3 wherein the pigments are light-stable pigments.

7, Process in accordance with Claim 1, 2 or 3 wherein the print carrier is selected from a printed paper, metal or fleece web.

8. Process in accordance with one of Claim 1, 2 or 3 wherein the print carrier is aluminum.

9. Process in accordance with Claim 1, 2 or 3 wherein the short-term contact for transfer of color has a duration of approximately 1 second and heat is applied at a temperature of 180-250° C and wherein the applied pressure increases considerably in the direction of conveyance.

10. Process in accordance with Claim 2 wherein the cooling in said temperature controlled stage of the process lasts 10-15 seconds during which the temperature of the foil is reduced from approximately 200-250°C to approximately 50-90°C.

11. Process in accordance with Claim 1, 2 or 3 wherein the melting-reservoir zone is formed in such a way that line pressure (P) increases steeply over length (1) from approximately 5-fold extrusion-tool-opening width (f) (or foil thickness (d) from approximately 1-60N/cm.

12. Process in accordance with Claim 3 wherein the slot is formed by the gap of two rollers, namely a conveying roller for the foil and a conveying roller for the print carrier.

13. Process in accordance with Claim 12 wherein the foil is introduced in an angle of approximately 10 - 15° relative to the center-line of the roller gap in the direction of the conveying roller of the print carrier.

14. Process in accordance with Claim 12 or 13 wherein the conveying roller of the foil is adjusted to a temperature of approximately 110° C and the conveying roller of the print carrier is adjusted to a temperature of approximately 70° C.

15. Process in accordance with Claim 1, 2 or 3 wherein the print carrier is pre-heated.

16. Process in accordance with Claim 1, 2 or 3 wherein the print carrier is conveyed by a conveying means comprising a rough surface roller.

17. Process in accordance with Claim 1, 2 or 3 wherein the side opposite the printing side of the covering is formed prefer-ably with scales.

18. Process in accordance with Claim 2 or 3 wherein the temperature-controlled cooling of the printed foil is accomplished by means of warm air.

19. Process in accordance with Claim 1, 2 or 3 wherein the printed foil is subject to at least one of the treatment steps comprising (a) high frequency Corona discharge and (b) non-oxidizing flame contact.

20. Process in accordance with Claim 1, 2 or 3 wherein the printed foil is treated chemically with a primer.

21. Process in accordance with Claim 1, 2 or 3 wherein the printed foil is laminated to a reinforcing material such as a light color plastic reinforced with glass fiber, by means of a transparent or light colored adhesive, preferably polyurethane adhesive.

22. Process in accordance with Claim 21, wherein the lamination of the foil to the reinforcing material is carried out under the influence of heat.

23. Apparatus for printing of web-like objects wherein a molten foil is continuously contacted with a print carrier comprising a pair of rollers for the formation of a roller gap, where one roller is partly wrapped by foil and the other roller is partly wrapped by the print carrier, and drive means for the to rollers for driving said rollers with essentially equal circumferential speed.

24. Apparatus in accordance with Claim 23 wherein the respective circumferential speed of the rollers is such that a wedge-type reservoir is formed in front of the roller gap by foil which emanates from an extrusion tool proximate thereto in the state of fusion, with the following dimensions.
s = d f = k1s l = k2s where s = roller gap width d = covering foil thickness 1 = roller gap length k1 is a constant in the range 1.0 to 1.2 k2 is a constant in the range l to 10.

25. Apparatus as defined in Claim 24 wherein 1 has a value in the range of about 0.5 to about 3.0 mm.

26. Apparatus in accordance with Claim 23 wherein at least the roller which conveys the foil is heated.

27. Apparatus in accordance with Claim 23, 24 or 26 wherein the roller which conveys the foil is equipped with an embossed pro-file.

28. Apparatus in accordance with Claim 23, 24 or 26 further comprising a tension controller for the print carrier and preheating means ahead of the conveying roller of the print carrier for heating the print carrier to approximately 50 - 70° C.

29. Apparatus in accordance with Claim 23, 24 or 26 further comprising tempering means for controllably reducing the temperature of said foil wherein said tempering means is located between said roller gap and a turn-around roller for withdrawal of said print carrier.

30. Apparatus in accordance with Claim 23, 24 or 26 further comprising pressure application means for maintaining contact of said foil and said print carrier, located between said roller gap and a turn-around roller for withdrawal of said print carrier.

31. Apparatus in accordance with Claim 23 further compris-ing heated roller means located before said pair of rollers fox heating said foil to a temperature intermediate the crystallite melting point and the fusion temperature thereof.

32. Apparatus in accordance with Claim 31 further com-prising heated roller means located before said pair of rollers for preheating said print carrier.

33. Apparatus in accordance with Claim 31 or 32 further comprising heated pressure rollers located after said pair of rollers for maintaining contact between said foil and said print carrier and simultaneously tempering said foil.